Despite the decline in coronary mortality that began in the mid-1960s, coronary disease remains the leading cause of death in the U.S. It is also the disease with the most rapidly escalating health care costs. An understanding of the factors contributing to this decline in mortality is necessary in order to develop a scientific basis for palliative and preventive programs. The causes of coronary heart kisease (CHD) are multifactorial. Therefore, no simple explanation for its decline can be expected. Secular trends in lifestyle, education, occupation mobility, and urban living have all probably had some influence on CHD incidence and mortality. At the same time, greater access to medical care, improvements in diagnostic and curative medicine, and the availability of new cardiovascular drugs for the treatment of risk factors, and coronary treatments have independently contributed to the decline. Major gaps in research exist which prevent the estimation of the contribution of these many factors much less the quantification of their interaction and/or interdependence. Most reported studies have followed specific population groups over a period of time noting the relation of CHD to risk factors and social/economic characteristics. These studies fail to take into account external trends occurring during the study period which not only make the risk factors of the study population "moving targets" but which may also affect the distribution of risk factors found in the general population over time, thus masking concommitants of the decline. Preliminary studies indicate secular trends in risk factors when individual of similar age but in different birth cohorts are compared. All groups show age-specific declines in total cholesterol, diastolic and systolic blood pressure between 1960 and 1968 at the time of the beginning of the decline in CHD mortality. Through the proposed research, the question of the impact of risk factors on the decline in CHD incidence and mortality can begin to be addressed. Logistic, multiple, and Cox regression techniques will enable the investigator to ascertain whether secular changes in risk factor levels or changes in the independent contribution of risk factors influenced this decline. These techniques will also be used to measure the contribution of occupation, education, medical care utilization, and other social and economic factors to changes in risk factor levels as well as changes in CHD incidence and mortality.